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Littérature scientifique sur le sujet « MRAS TECHNIQUE »

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Publié le 11 septembre 2023

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Articles de revues sur le sujet "MRAS TECHNIQUE"

1

Ghany, M. A. Abdel, et Mohamed A. Shamseldin. « Model reference self-tuning fractional order PID control based on for a power system stabilizer ». International Journal of Power Electronics and Drive Systems (IJPEDS) 11, no 3 (1 septembre 2020) : 1333. http://dx.doi.org/10.11591/ijpeds.v11.i3.pp1333-1343.

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<p><span lang="EN-US">This paper presents a novel approach of self-tuning for a Modified Fractional Order PID (MFOPID) depends on the Model Reference Adaptive System (MRAS). The proposed self-tuning controller is applied to Power System Stabilizer (PSS). Takaji-Sugeno (TS) fuzzy logic technique is used to construct the MFOPID controller. The objective of MRAS is to update the five parameters of Takaji-Sugeno Modified FOPID (TSMFOPID) controller online. For different operating points of PSS, MRAS is applied to investigate the effectiveness of proposed controllers. The harmony optimization technique used to obtain the optimal parameters of TSMFOPID controllers and MRAS parameters. For different operating points with different disturbance under parameters variations the simulation results are obtained. This is to show that Self-Tuning of TSMFOPID based on (MRAS) have better performance than the fixed parameters TSMOFOPID controller.</span></p>
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2

Qu, Zhi Yong, et Zheng Mao Ye. « Speed Regulation of a Permanent Magnet Synchronous Motor via Model Reference Adaptive Control ». Advanced Materials Research 268-270 (juillet 2011) : 513–16. http://dx.doi.org/10.4028/www.scientific.net/amr.268-270.513.

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A speed estimation technique for the permanent magnet synchronous motor drive is presented in this paper A Model Reference Adaptive System (MRAS) has been formed using the voltage and current to estimate the speed. It has been shown that such unique MRAS offers several desirable features. The proposed technique is completely independent of stator resistance and is less parameter sensitive, as the estimation-algorithm is only dependent on q-axis stator inductance. Also, the method requires less computational effort as the simplified expressions are used in the MRAS. The stability of the proposed system is achieved through Popov’s Hyperstability criteria. Matlab simulation results are presented to validate the proposed technique.
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R, Mini, Shabana Backer P., B. Hariram Satheesh et Dinesh M. N. « Low Speed Estimation of Sensorless DTC Induction Motor Drive Using MRAS with Neuro Fuzzy Adaptive Controller ». International Journal of Electrical and Computer Engineering (IJECE) 8, no 5 (1 octobre 2018) : 2691. http://dx.doi.org/10.11591/ijece.v8i5.pp2691-2702.

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<p>This paper presents a closed loop Model Reference Adaptive system (MRAS) observer with artificial intelligent Nuero fuzzy controller (NFC) as the adaptation technique to mitigate the low speed estimation issues and to improvise the performance of the Sensorless Direct Torque Controlled (DTC) Induction Motor Drives (IMD). Rotor flux MRAS and reactive power MRAS with NFC is explored and detailed analysis is carried out for low speed estimation. Comparative analysis between rotor flux MRAS and reactive power MRAS with PI as well as NFC as adaptive controller is performed and results are presented in this paper. The comparative analysis among these four speed estimation methods shows that reactive power MRAS with NFC as adaptation mechanism shows reduced speed estimation error and actual speed error at steady state operating conditions when the drive is subjected to low speed operation. Simulation carried out using MATLAB-Simulink software to validate the performance of the drive especially at low speeds with rated and variable load conditions.</p>
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4

Yang, Li Yong, et Liu Shuo. « Parameter Tuning for Sensorless Induction-Motor Drive Use Stator-Current-Based MRAS Estimator ». Advanced Materials Research 383-390 (novembre 2011) : 352–57. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.352.

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This paper proposes an analysis of the vector-controlled induction-motor (IM) drive with a novel modelreference adaptive system (MRAS)-type rotor speed estimator .In this scheme which stator-current-error-based MRAS is used instead of the rotor-flux-error-based MRAS scheme,an stator-current-error-based MRAS is used for estimate the IM rotor speed ,and this is used as feedback signals for the indirect field oriented control technique (IFOC),which is a widely used control method for Induction Motor drive (IM). For improving the dynamic characteristic of the system, it is very improtant for vector control to proceed parameter tuning.Some experimental results based on TMS 320F2812 DSP are provided to verify the proposed system performance in a low speed at no-load and load conditions.
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5

Asfu, Workagegn Tatek. « Stator Current-Based Model Reference Adaptive Control for Sensorless Speed Control of the Induction Motor ». Journal of Control Science and Engineering 2020 (14 octobre 2020) : 1–17. http://dx.doi.org/10.1155/2020/8954704.

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This paper described that the stator current-based model reference adaptive system (MRAS) speed estimator is used for the induction motor (IM) indirect vector speed control without a mechanical speed sensor. Due to high sensitivity of motor parameters variation at low speed including zero, stability analysis of MRAS design is performed to correct any mismatch parameters value in the MRAS performed to estimate the motor speed at these values. As a result, the IM sensorless control can operate over a wide range including zero speed. The performance of the stator current-based MRAS speed estimator was analyzed in terms of speed tracking capability, torque response quickness, low speed behavior, step response of drive with speed reversal, sensitivity to motor parameter uncertainty, and speed tracking ability in the regenerative mode. The system gives a good performance at no-load and loaded conditions with parameter variation. The stator current-based MRAS estimator sensorless speed control technique can make the hardware simple and improve the reliability of the motor without introducing a feedback sensor, and it becomes more important in the modern AC IM. The sensorless vector control operation has been verified by simulation on Matlab and experimentally using Texas Instruments HVMTRPFCKIT with TMS320 F28035 DSP card and 0.18 kw AC IM.
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6

Ho, Sang Dang, Petr Palacky, Martin Kuchar, Pavel Brandstetter et Cuong Dinh Tran. « Particle swarm optimization-based stator resistance observer for speed sensorless induction motor drive ». International Journal of Electrical and Computer Engineering (IJECE) 11, no 1 (1 février 2021) : 815. http://dx.doi.org/10.11591/ijece.v11i1.pp815-826.

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This paper presents a different technique for the online stator resistance estimation using a particle swarm optimization (PSO) based algorithm for rotor flux oriented control schemes of induction motor drives without a rotor speed sensor. First, a conventional proportional-integral controller-based stator resistance estimation technique is used for a speed sensorless control scheme with two different model reference adaptive system (MRAS) concepts. Finally, a novel method for the stator resistance estimation based on the PSO algorithm is presented for the two MRAS-type observers. Simulation results in the Matlab/Simulink environment show good adaptability of the proposed estimation model while the stator resistance is varied to 200% of the nominal value. The results also confirm more accurate stator resistance and rotor speed estimation in comparison with the conventional technique.
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Kumar Samal, Sidhartha, Smrutisikha Jena, Bibhu Prasad Ganthia, S. Kaliappan, M. Sudhakar et S. K. Sriram Kalyan. « Sensorless Speed Contorl of Doubly-Fed Induction Machine Using Reactive Power Based MRAS ». Journal of Physics : Conference Series 2161, no 1 (1 janvier 2022) : 012069. http://dx.doi.org/10.1088/1742-6596/2161/1/012069.

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Abstract A sensorless speed control method for doubly-fed induction machine (DFIM) operating with constant frequency but in variable speed mode is presented in this project work. The control method is based on rotor speed estimation technique by a reactive power model reference adaptive system (MRAS) observer. The presented technique does not depend on any kind of flux evaluation and also independent to the resistance variation of either stator or rotor. The MRAS observer has a capacity for speed catching operation. PI controller is designed and also optimized using algorithm for better dynamic behaviour of the machine. MATLAB Simulink model and the simulation results are shown to check the effectiveness of the observer and also of the controller.
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8

Sedhuraman, K., S. Himavathi et A. Muthuramalingam. « Neural learning adaptive system using simplified reactive power reference model based speed estimation in sensorless indirect vector controlled induction motor drives ». Archives of Electrical Engineering 62, no 1 (1 mars 2013) : 25–41. http://dx.doi.org/10.2478/aee-2013-0003.

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Abstract This paper presents a novel speed estimator using Reactive Power based Model Reference Neural Learning Adaptive System (RP-MRNLAS) for sensorless indirect vector controlled induction motor drives. The Model Reference Adaptive System (MRAS) based speed estimator using simplified reactive power equations is one of the speed estimation method used for sensor-less indirect vector controlled induction motor drives. The conventional MRAS speed estimator uses PI controller for adaptation mechanism. The nonlinear mapping capability of Neural Network (NN) and the powerful learning algorithms have increased the applications of NN in power electronics and drives. This paper proposes the use of neural learning algorithm for adaptation in a reactive power technique based MRAS for speed estimation. The proposed scheme combines the advantages of simplified reactive power technique and the capability of neural learning algorithm to form a scheme named “Reactive Power based Model Reference Neural Learning Adaptive System” (RP-MRNLAS) for speed estimator in Sensorless Indirect Vector Controlled Induction Motor Drives. The proposed RP-MRNLAS is compared in terms of accuracy, integrator drift problems and stator resistance versions with the commonly used Rotor Flux based MRNLAS (RF-MRNLAS) for the same system and validated through Matlab/Simulink. The superiority of the RP-MRNLAS technique is demonstrated.
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9

SAIHI, Lakhdar, Youcef Bakou, Fateh Ferroudji, Abdelkader Hadidi et Ibrahim Oulimar. « A Hybrid H∞-MRAS Observer of Wind Turbines Conversion Systems based on DFIG ». Algerian Journal of Renewable Energy and Sustainable Development 4, no 01 (15 juin 2022) : 101–10. http://dx.doi.org/10.46657/ajresd.2022.4.1.10.

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This study proposes the robust sensor-less advanced frequency control (robust H∞ control) of the system of wind turbine based on a doubly fed induction generator (DFIG), the power exchange between the machine stator and the network is achieved by applying the rotor of DFIG via a bidirectional converter. The purpose of the control is to regulate the stator active and reactive power produced by the DFIG using a robust H∞ controller. The Model reference and adaptive system (MRAS-Observer) uses the error between the actual and estimated values ​​(voltage/current) to construct the observed mechanical parameters (speed and position) value, this technique uses two separate models: the first is the reference model, the second is the adjustable mode. The error between these models is used by the adaptive mechanism. The adjustment mechanism is mostly a PI controller, to improve the performance and robustness of the classical MRAS observer, we replace the classical PI controller with a robust H∞ controller. The results simulations confirm the robustness of the sensorless robust H∞ control using the H∞-MRAS observer compared to conventional MRAS, which improves the quality and quantity of generated power.
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Fnaiech, Mohamed Amine, Jaroslaw Guzinski, Mohamed Trabelsi, Abdellah Kouzou, Mohamed Benbouzid et Krzysztof Luksza. « MRAS-Based Switching Linear Feedback Strategy for Sensorless Speed Control of Induction Motor Drives ». Energies 14, no 11 (26 mai 2021) : 3083. http://dx.doi.org/10.3390/en14113083.

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This paper presents a newly designed switching linear feedback structure of sliding mode control (SLF-SMC) plugged with an model reference adaptive system (MRAS) based sensorless field-oriented control (SFOC) for induction motor (IM). Indeed, the performance of the MRAS depends mainly on the operating point and the parametric variation of the IM. Hence, the sliding mode control (SMC) could be considered a good control alternative due to its easy implementation and robustness. Simulation and experimentation results are presented to show the superiority of the proposed SLF-SMC technique in comparison with the classical PI controller under different speed ranges and inertia conditions.
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Thèses sur le sujet "MRAS TECHNIQUE"

1

Rivera, Frances. « The Use of Proteomic Techniques to Study the Physiology and Virulence of Staphylococcus aureus ». Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3603.

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Staphylococcus aureus is a bacterial pathogen that is believed to be the most common agent of human infectious disease, causing conditions ranging from common skin lesions to life-threatening illnesses. S. aureus has also shown a remarkable ability to develop resistance to antimicrobial treatment, making infections difficult to treat. In the post-genomic era, proteomic studies analyzing the protein complement of a genome in a particular organism at any given time, have gained real significance. This result is largely due to dynamic changes in protein expression profiles which can lead wide alterations in physiology and behavior. For proteomics, it is necessary to maximize protein concentration and to devise a method that can be easily employed and provide reproducible results. Most proteomic studies of S. aureus involve 2D gel electrophoresis (2-DE); however, 2-DE has many drawbacks. Proteins that are too large, hydrophobic, acidic, or basic are poorly resolved. Multi-dimensional protein identification (MudPIT) allows complex protein samples to be analyzed in solution. As yet, there has not been a study involving solely 2D liquid chromatography followed by mass spectrometric analysis in S. aureus ; therefore we sought to catalogue the intracellular proteome and secretome of a commonly used and well-studied lab strain, SH1000. This was conducted during post-exponential and stationary phases of growth so as to understand its adaptation over time by utilizing differential protein synthesis. We found cytoplasmic proteins involved in glycolysis to be highly expressed in post-exponential phase while proteins involved in tricarboxylic acid cycle to be prevalent in stationary phase. We also found production of agr-regulated secreted toxins and proteases to be upregulated in stationary phase. In addition to this we employed proteomic approaches to quantitatively profile the secretomes of leading clinical isolates of S. aureus, as such a study is currently lacking. These included the two most common hospital-associated S. aureus strains (USA100 and USA200), and the two most common community-associated S. aureus strains (USA300 and USA400). We found agr-regulated proteins are generally upregulated in CA-MRSA strains USA300 and USA400 and surface-associated proteins to be upregulated in HA-MRSA strains USA100 and USA200. This finding concurs with literature regarding transcriptomic studies showing a hyperactive agr in CA-MRSA strains compared to HA-MRSA strains.
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2

Akin, Bilal. « State Estimation Techniques For Speed Sensorless Field Oriented Control Of Induction Motors ». Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1055953/index.pdf.

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This thesis presents different state estimation techniques for speed sensorlees field oriented control of induction motors. The theoretical basis of each algorithm is explained in detail and its performance is tested with simulations and experiments individually. First, a stochastical nonlinear state estimator, Extended Kalman Filter (EKF) is presented. The motor model designed for EKF application involves rotor speed, dq-axis rotor fluxes and dq-axis stator currents. Thus, using this observer the rotor speed and rotor fluxes are estimated simultaneously. Different from the widely accepted use of EKF, in which it is optimized for either steady-state or transient operations, here using adjustable noise level process algorithm the optimization of EKF has been done for both states
the steady-state and the transient-state of operations. Additionally, the measurement noise immunity of EKF is also investigated. Second, Unscented Kalman Filter (UKF), which is an updated version of EKF, is proposed as a state estimator for speed sensorless field oriented control of induction motors. UKF state update computations, different from EKF, are derivative free and they do not involve costly calculation of Jacobian matrices. Moreover, variance of each state is not assumed Gaussian, therefore a more realistic approach is provided by UKF. In this work, the superiority of UKF is shown in the state estimation of induction motor. Third, Model Reference Adaptive System is studied as a state estimator. Two different methods, back emf scheme and reactive power scheme, are applied to MRAS algorithm to estimate rotor speed. Finally, a flux estimator and an open-loop speed estimator combination is employed to observe stator-rotor fluxes, rotor-flux angle and rotor speed. In flux estimator, voltage model is assisted by current model via a closed-loop to compensate voltage model&rsquo
s disadvantages.
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3

Besbes, Ahmed. « Image segmentation using MRFs and statistical shape modeling ». Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00594246.

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Nous présentons dans cette thèse un nouveau modèle statistique de forme et l'utilisons pour la segmentation d'images avec a priori. Ce modèle est représenté par un champ de Markov. Les noeuds du graphe correspondent aux points de contrôle situés sur le contour de la forme géométrique, et les arêtes du graphe représentent les dépendances entre les points de contrôle. La structure du champ de Markov est déterminée à partir d'un ensemble de formes, en utilisant des techniques d'apprentissage de variétés et de groupement non-supervisé. Les contraintes entre les points sont assurées par l'estimation des fonctions de densité de probabilité des longueurs de cordes normalisées. Dans une deuxième étape, nous construisons un algorithme de segmentation qui intègre le modèle statistique de forme, et qui le relie à l'image grâce à un terme région, à travers l'utilisation de diagrammes de Voronoi. Dans cette approche, un contour de forme déformable évolue vers l'objet à segmenter. Nous formulons aussi un algorithme de segmentation basé sur des détecteurs de points d'intérêt, où le terme de régularisation est lié à l'apriori de forme. Dans ce cas, on cherche à faire correspondre le modèle aux meilleurs points candidats extraits de l'image par le détecteur. L'optimisation pour les deux algorithmes est faite en utilisant des méthodes récentes et efficaces. Nous validons notre approche à travers plusieurs jeux de données en 2D et en 3D, pour des applications de vision par ordinateur ainsi que l'analyse d'images médicales.
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Lim, Tien Tze. « Molecular characterization of Malaysian methicillin-resistant Staphylococcus aureus ». Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/2635.

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Seventy-four methicillin-resistant Staphylococcus aureus (MRSA) from two Malaysian hospitals were characterised by both phenotypic and genotypic techniques. These isolates were collected over an 18 year time period in the years, 1982, 1989, 1994 and 2000. All of the Malaysian MRSA isolates were found to be multiresistant and resistant to at least five different antimicrobial agents. Over 30% of them were non-typable by the International Basic Set of bacteriophages. The majority of the typable isolates were susceptible to the group III phages, especially phage 85. The majority of the isolates carried one to six plasmids. Only two isolates were plasmid free. The plasmid profiles of these isolates, other than the 1982 isolates, were very similar to each other. Contour-clamped homogeneous electric field (CHEF) gel electrophoresis was used to examine the genetic relatedness of the isolates. Twenty-six CHEF patterns were found among the isolates. These CHEF patterns were closely related to each other. The predominant CHEF pattern A was found in the 1982, 1989 and 1994 isolates. The CHEF patterns of the year 2000 isolates were different to CHEF pattern A, but still closely related. All of the isolates were found to carry the Allotype III SCCmec and have coagulase-gene type 24. Multilocus sequence typing was preformed on the isolates with CHEF pattern A collected in different years. These isolates were found to have either sequence type 239 (ST239), or its single locus variant. The predominant Malaysian clone belongs to the pandemic clone ST239-MRSA-III that is pandemic in Asian countries. (Enright, 2003, Ko et al., 2005).A 1.5 kb cryptic plasmid found in Malaysian isolates was indistinguishable from a cryptic plasmid found in an Australian isolate. A 3.0 kb cryptic plasmid found in Malaysian isolates was undistinguishable from a 3.0 kb plasmid found in Singaporean isolates. Class II multiresistance plasmids of 28, 30.5 and 35 kb were commonly found together in many Malaysian MRSA isolates. Both the 28 and 30.5 kb plasmids encode resistance to the heavy-metals and nucleic acid-binding (NAB) compounds. The 35 kb plasmid carries heavy-metal and NAB resistance but also encodes β-lactamase. Structurally these three plasmids are almost identical and probably have the same origin. The differences observed between these plasmids is probably due to excision or partial deletion of the β-lactamase transposon of the original plasmid. The 28 kb plasmid is identical to the 28 kb plasmid of Singaporean and some Australian isolates. A 20 kb plasmid in Indonesian isolates was found to be closely related to these three plasmids. A conjugative plasmid, pWBG707, conferring trimethoprim-resistance was found in Malaysian isolates. It did not carry either of the two staphylococcal trimethoprim-resistance genes, dfrA and dfrD. (Lyon and Skurray, 1987, Dale et al., 1995b) It either encodes a novel resistance gene or the recently discovered dfrG gene. (Sekiguchi et al., 2005) pWBG707 was also found to mobilise a small 3.0 kb kanamycin-resistance plasmid during conjugation.The mecR1 and mecI genes regulating the transcription of the methicillin-resistance gene, mecA, were also examined in the isolates. The Malaysian isolate, WBG7422, with the predominant CHEF pattern A has a nonsense mutation in its mecI gene that disables it. However, its mecR1 gene is intact. The eastern Australia MRSA (EA MRSA), WBG525, has a CHEF pattern that is closely related to the Malaysian predominant CHEF pattern A and its mecI gene has a mutation identical to the Malaysian isolate. Unlike the Malaysian isolate however, its mecR1 gene has a 166 bp deletion. Both WBG7422 and WBG525 express Class III heterogeneous methicillin resistance. However, WBG525 has more highly resistant cell in its population than WBG7422. The loss of aminoglycoside resistance, together with c. 114 kb of chromosomal DNA, was observed in some Malaysian isolates. The deleted segment was found to carry the aacA-aphD gene that encodes a bifunctional aminoglycoside-modifying enzyme conferring resistance to many of the aminoglycosides. The Malaysian isolates were compared with MRSA from different countries. These MRSA included 18 epidemic MRSA (EMRSA) from the United Kingdom, 15 Australian nosocomial MRSA, five classical MRSA, 22 community-acquired MRSA (CMRSA) from Australia and New Zealand and 46 nosocomial MRSAs from eight Asian-Pacific countries and South Africa. These Asian-Pacific countries were Australia, PR China, Hong Kong, Indonesia, Japan, Philippines, Singapore and Taiwan.The CHEF patterns of most of the Asian-Pacific and South African isolates were closely related to the Malaysian isolates. Isolates from Singapore, Indonesia and Philippines were found to have an identical CHEF pattern to the Malaysian CHEF patterns A5. The Asian-Pacific and South African isolates, including the Malaysian isolates, were found to be closely related to EMRSA-1, -4 and -7. These EMRSA belong to the ST239-MRSA-III clone and are coagulase-gene type 24. The isolates from Japan were the only Asian-Pacific isolates not related to the other Asian-Pacific isolates and EMRSAs. EMRSA-1 and EA MRSA have the same 166 bp deletion in their mecR1 gene. Both of these strains have closely related CHEF patterns, the same sequence type, coagulase-gene type and SCCmec. These results indicate that these two strains belongs to the same clone and confirms the international spread of this clone in the early 1980s. However, the Malaysian isolates have CHEF patterns that are more closely related to EMRSA-4 than to EMRSA-1. Similar to the Malaysian isolates EMRSA-4 has an intact mecR1 gene. The CMRSA isolates were not related to any of the nosocomial MRSA. They also have very diverse genetic backgrounds but carry less diverse SCCmec allotypes. Most of the CMRSA carry either Allotype IV or V SCCmec These results show that the spread of Malaysian MRSA is due to a single clonal expansion. Infection control measures would have to have been more efficient if this clone was to have been contained. The Malaysian epidemic clone is the Asian pandemic clone, ST239-MRSA-III. The Malaysian isolates and EMRSA-4 probably share the same ancestor.The presence of the same MRSA strain in Malaysian hospitals and in the hospitals of neighbouring countries indicates that the inter-hospital spread of an epidemic MRSA has occurred. This observation also suggests that the infection control measures in Malaysian hospitals have not been totally effective. The ineffectiveness of infection control has left Malaysian hospitals vulnerable to the future importation of new pandemic clones and/or highly virulent or resistant clones.
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5

Lim, Tien Tze. « Molecular characterization of Malaysian methicillin-resistant Staphylococcus aureus ». Curtin University of Technology, School of Biomedical Sciences, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17817.

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Seventy-four methicillin-resistant Staphylococcus aureus (MRSA) from two Malaysian hospitals were characterised by both phenotypic and genotypic techniques. These isolates were collected over an 18 year time period in the years, 1982, 1989, 1994 and 2000. All of the Malaysian MRSA isolates were found to be multiresistant and resistant to at least five different antimicrobial agents. Over 30% of them were non-typable by the International Basic Set of bacteriophages. The majority of the typable isolates were susceptible to the group III phages, especially phage 85. The majority of the isolates carried one to six plasmids. Only two isolates were plasmid free. The plasmid profiles of these isolates, other than the 1982 isolates, were very similar to each other. Contour-clamped homogeneous electric field (CHEF) gel electrophoresis was used to examine the genetic relatedness of the isolates. Twenty-six CHEF patterns were found among the isolates. These CHEF patterns were closely related to each other. The predominant CHEF pattern A was found in the 1982, 1989 and 1994 isolates. The CHEF patterns of the year 2000 isolates were different to CHEF pattern A, but still closely related. All of the isolates were found to carry the Allotype III SCCmec and have coagulase-gene type 24. Multilocus sequence typing was preformed on the isolates with CHEF pattern A collected in different years. These isolates were found to have either sequence type 239 (ST239), or its single locus variant. The predominant Malaysian clone belongs to the pandemic clone ST239-MRSA-III that is pandemic in Asian countries. (Enright, 2003, Ko et al., 2005).
A 1.5 kb cryptic plasmid found in Malaysian isolates was indistinguishable from a cryptic plasmid found in an Australian isolate. A 3.0 kb cryptic plasmid found in Malaysian isolates was undistinguishable from a 3.0 kb plasmid found in Singaporean isolates. Class II multiresistance plasmids of 28, 30.5 and 35 kb were commonly found together in many Malaysian MRSA isolates. Both the 28 and 30.5 kb plasmids encode resistance to the heavy-metals and nucleic acid-binding (NAB) compounds. The 35 kb plasmid carries heavy-metal and NAB resistance but also encodes β-lactamase. Structurally these three plasmids are almost identical and probably have the same origin. The differences observed between these plasmids is probably due to excision or partial deletion of the β-lactamase transposon of the original plasmid. The 28 kb plasmid is identical to the 28 kb plasmid of Singaporean and some Australian isolates. A 20 kb plasmid in Indonesian isolates was found to be closely related to these three plasmids. A conjugative plasmid, pWBG707, conferring trimethoprim-resistance was found in Malaysian isolates. It did not carry either of the two staphylococcal trimethoprim-resistance genes, dfrA and dfrD. (Lyon and Skurray, 1987, Dale et al., 1995b) It either encodes a novel resistance gene or the recently discovered dfrG gene. (Sekiguchi et al., 2005) pWBG707 was also found to mobilise a small 3.0 kb kanamycin-resistance plasmid during conjugation.
The mecR1 and mecI genes regulating the transcription of the methicillin-resistance gene, mecA, were also examined in the isolates. The Malaysian isolate, WBG7422, with the predominant CHEF pattern A has a nonsense mutation in its mecI gene that disables it. However, its mecR1 gene is intact. The eastern Australia MRSA (EA MRSA), WBG525, has a CHEF pattern that is closely related to the Malaysian predominant CHEF pattern A and its mecI gene has a mutation identical to the Malaysian isolate. Unlike the Malaysian isolate however, its mecR1 gene has a 166 bp deletion. Both WBG7422 and WBG525 express Class III heterogeneous methicillin resistance. However, WBG525 has more highly resistant cell in its population than WBG7422. The loss of aminoglycoside resistance, together with c. 114 kb of chromosomal DNA, was observed in some Malaysian isolates. The deleted segment was found to carry the aacA-aphD gene that encodes a bifunctional aminoglycoside-modifying enzyme conferring resistance to many of the aminoglycosides. The Malaysian isolates were compared with MRSA from different countries. These MRSA included 18 epidemic MRSA (EMRSA) from the United Kingdom, 15 Australian nosocomial MRSA, five classical MRSA, 22 community-acquired MRSA (CMRSA) from Australia and New Zealand and 46 nosocomial MRSAs from eight Asian-Pacific countries and South Africa. These Asian-Pacific countries were Australia, PR China, Hong Kong, Indonesia, Japan, Philippines, Singapore and Taiwan.
The CHEF patterns of most of the Asian-Pacific and South African isolates were closely related to the Malaysian isolates. Isolates from Singapore, Indonesia and Philippines were found to have an identical CHEF pattern to the Malaysian CHEF patterns A5. The Asian-Pacific and South African isolates, including the Malaysian isolates, were found to be closely related to EMRSA-1, -4 and -7. These EMRSA belong to the ST239-MRSA-III clone and are coagulase-gene type 24. The isolates from Japan were the only Asian-Pacific isolates not related to the other Asian-Pacific isolates and EMRSAs. EMRSA-1 and EA MRSA have the same 166 bp deletion in their mecR1 gene. Both of these strains have closely related CHEF patterns, the same sequence type, coagulase-gene type and SCCmec. These results indicate that these two strains belongs to the same clone and confirms the international spread of this clone in the early 1980s. However, the Malaysian isolates have CHEF patterns that are more closely related to EMRSA-4 than to EMRSA-1. Similar to the Malaysian isolates EMRSA-4 has an intact mecR1 gene. The CMRSA isolates were not related to any of the nosocomial MRSA. They also have very diverse genetic backgrounds but carry less diverse SCCmec allotypes. Most of the CMRSA carry either Allotype IV or V SCCmec These results show that the spread of Malaysian MRSA is due to a single clonal expansion. Infection control measures would have to have been more efficient if this clone was to have been contained. The Malaysian epidemic clone is the Asian pandemic clone, ST239-MRSA-III. The Malaysian isolates and EMRSA-4 probably share the same ancestor.
The presence of the same MRSA strain in Malaysian hospitals and in the hospitals of neighbouring countries indicates that the inter-hospital spread of an epidemic MRSA has occurred. This observation also suggests that the infection control measures in Malaysian hospitals have not been totally effective. The ineffectiveness of infection control has left Malaysian hospitals vulnerable to the future importation of new pandemic clones and/or highly virulent or resistant clones.
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Susic, Semir. « Beyond Good and Evil : An essay on the combination of ideas and aesthetics in George Bernard Shaw's Mrs Warren’s Profession ». Thesis, Stockholm University, Department of History of Literature and History of Ideas, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8314.

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The objective of this essay is to approach a larger comprehension of the drama of George Bernard Shaw. The essay studies the combination of ideas and aesthetics in the play Mrs Warren’s Profession; how theatrical and mainly literary aesthetics interplay with political ideas and what the consequence of this combination is. The study illustrates that the dramatic method consists of using ideas as effective theatrical tools to move the reader/viewer by thought and not by sentiment. The study also illustrates that a key to understanding Shaw’s drama can be found in the construction of operas and symphonies; musical theoretic constructions are an integrated dramatic technique in Mrs Warren’s Profession. The study shows that it is a play with a political and social purpose; to raise awareness of the mechanisms of prostitution. The play does not use simplifications in terms of good and evil. It questions conventionality, unveils social hypocrisy and attempts to disillusion the reader/viewer. The antithesis between realism and idealism is an important source of dynamics and constitutes one of the principal aesthetical constructions.

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Rao, Anita. « High resolution magnetic resonance angiography (mra) of the renal vasculature : development of improved acquisition and post- processing techniques / ». The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487940308432037.

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Ortega-Martorell, Sandra. « On the use of advanced pattern recognition techniques for the analysis of MRS and MRSI data in neuro-oncology ». Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/284491.

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El cáncer es una de las principales causas de muerte en el mundo. Los tumores cerebrales tienen una incidencia relativamente baja en comparación con otras patologías cancerígenas más generalizadas, pero la prognosis de algunos es muy pobre, contribuyendo significativamente a su morbilidad. La gestión clínica de una masa anormal en el cerebro es materia delicada y difícil, por lo que los expertos han de basarse en mediciones indirectas no invasivas de las características del tumor y de su crecimiento. En la práctica radiológica actual, estas mediciones se realizan a menudo mediante técnicas de resonancia magnética (MR), como la imagen (MRI) y la espectroscopia (MRS). La vasta información contenida en las señales de MR les hace ideales para la aplicación de técnicas de reconocimiento de patrones (PR). Durante las dos últimas décadas, estas técnicas se han aplicado con éxito al problema de la extracción de conocimiento a partir de datos de tumores cerebrales humanos, para su diagnóstico y pronóstico. No obstante, la discriminación de algunos tipos y subtipos de tumores, así como la delimitación precisa del área tumoral, continúan siendo un reto para los investigadores. En esta tesis, abordamos tales retos mediante la aplicación de un conjunto de técnicas avanzadas de PR. En primera instancia, se implementaron una variedad de técnicas comunes y bien conocidas en una herramienta integrada de software. Esta fue utilizada en tareas de reducción de dimensionalidad (DR), clasificación y evaluación de modelos, para el desarrollo de clasificadores apropiados para analizar datos de MRS. Posteriormente, se profundizó en el desarrollo de métodos de extracción de características (FE), para proponer un método que proporciona prototipos de señal interpretables a partir de los datos de MRS. En una siguiente fase, dos técnicas de descomposición espectral fueron utilizadas para extraer fuentes de MRS e identificar la que proporciona mejores resultados en el contexto de problemas de neuro-oncología, utilizando datos de MRS de un solo vóxel (SV). El mejor y más adecuado método de extracción de fuentes resultante se utilizó posteriormente para derivar fuentes correlacionadas con los espectros promedio de los tipos de tejidos estudiados. El primer enfoque se aplicó también en el contexto de datos de múltiples vóxeles (MV), donde se propone un mecanismo para delimitar la zona patológica del tumor. Las contribuciones se pueden resumir de la siguiente manera. En primer lugar, el desarrollo de una herramienta de software que ha permitido reproducir clasificadores previamente publicados, así como probar nuevas hipótesis. También se ha contribuido con un método de FE, cuyo rendimiento es comparable a su contraparte más comúnmente utilizada en el análisis de datos de MRS, al tiempo que mejora su interpretación. Por otra parte, hemos identificado la variante de descomposición espectral que mejor se adapta al análisis de datos de SV MRS, llamada Convex Non-negative Matrix Factorisation (NMF), mostrando su capacidad para discriminar entre tejido sano, necrosis y tumor en proliferación activa, con resultados que son comparables a los obtenidos en modo supervisado. Con los datos de MV, los resultados obtenidos evidencian que es posible conseguir una delimitación precisa de la zona patológica mediante la aplicación de Convex-NMF. Con esta tesis, ofrecemos una herramienta a radiólogos espectroscopistas para facilitar el desarrollo de clasificadores para el análisis de datos de MRS, en un amplio grupo de tipos tumorales. También ofrecemos una alternativa no supervisada para mejorar la discriminación entre tipos y subtipos tumorales, colocando este enfoque un paso por delante de los métodos supervisados clásicos. Esto nos ha permitido hacer frente a una de las principales fuentes de incertidumbre en el manejo clínico de tumores cerebrales: la dificultad de delimitar adecuadamente el área patológica.
Cancer is a leading cause of death worldwide. Tumours of the Central Nervous System and, among them, brain tumours have a relatively low incidence as compared to other more widespread cancer pathologies, but the prognosis of some of them is very poor, contributing significantly to morbidity. The clinical management of an abnormal mass in the brain is sensitive and difficult, making experts to rely on non-invasive indirect measurements of the tumour characteristics and growth. In current radiological practice, these data measurements are often provided by magnetic resonance (MR) techniques, such as imaging (MRI) and spectroscopy (MRS). The rich information contained in MR signals makes them ideally suited to the application of pattern recognition (PR) techniques. Over the last two decades, these techniques have been successfully used to address the problem of knowledge extraction from human brain tumour data, for their diagnosis and prognosis. Nevertheless, the discrimination of some tumour types and subtypes, along with the accurate delimitation of the tumour area, remained challenging. In this thesis, we approach these challenges using a set of advanced PR techniques. A variety of common and well-known dimensionality reduction (DR), classification, and evaluation methods are first gathered in a software tool, used for the development of classifiers that are suitable for the analysis of MRS data. We then delve into the feature extraction (FE) family of DR methods to propose a method that is robust in the presence of noise, not prone to overfitting, and which also provides interpretation of the extracted MRS signal prototypes. Two spectral decomposition techniques, in different algorithmic variants, are subsequently used to extract the sources of the MRS signals and identify the one that provides better results in the context of neuro-oncology, using single-voxel (SV) MRS data. The best and most adequate source extraction method is then used to derive sources correlated with the mean spectra of known tissue types. The former, an unsupervised approach, is also applied in this thesis in the multi-voxel (MV) context, where we propose a mechanism for delimiting the pathological area of the tumour. The contributions of this thesis can be summarised as follows. First, the development of a software tool allowed us to reproduce previously published MRS-based classifiers, and test new hypotheses that led to new publications. We also contributed a FE method, whose performance is comparable to its most commonly used counterpart in MRS data analysis, while improving on the interpretability. Moreover, we identified the spectral decomposition variant that best suits the analysis of SV MRS data, namely Convex Non-negative Matrix Factorisation (NMF), and showed its ability to discriminate between healthy tissue, necrosis, and actively proliferating tumour, with results that are comparable to those obtained in fully supervised mode. For MV data, we successfully benchmarked alternative spectral decomposition methods, and provided evidence supporting that very accurate delimitation can be achieved through the application of Convex-NMF. With this thesis, we provide spectroscopists with a tool that facilitates the development of classifiers for the analysis of MRS data, for a large group of tumour types; allowing them to concentrate on the interpretation of the results, without requiring a specialised mathematical expertise for testing their hypotheses. We also provide an unsupervised alternative to improve the discrimination between tumour types and subtypes, placing this approach one step ahead of classical label-requiring supervised methods for detection of the increasingly recognised molecular subtype heterogeneity within human brain tumours. This also allowed us to accurately tackle one of the main sources of uncertainty in the clinical management of brain tumours, which is the difficulty of appropriately delimiting the pathological area.
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Xiang, Bo. « Knowledge-based image segmentation using sparse shape priors and high-order MRFs ». Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2013. http://www.theses.fr/2013ECAP0066/document.

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Nous présentons dans cette thèse une approche nouvelle de la segmentation d’images, avec des descripteurs a priori utilisant des champs de Markov d’ordre supérieur. Nous représentons le modèle de forme par un graphe de distribution de points qui décrit les informations a priori des invariants de pose grâce à des cliques L1 discrètes d’ordre supérieur. Chaque clique de triplet décrit les variations statistiques locales de forme par des mesures d’angle,ce qui assure l’invariance aux transformations globales (translation, rotation et échelle). L’apprentissage d’une structure de graphe discret d’ordre supérieur est réalisé grâce à l’apprentissage d’un champ de Markov aléatoire utilisant une décomposition duale, ce qui renforce son efficacité tout en préservant sa capacité à rendre compte des variations.Nous introduisons la connaissance a priori d’une manière innovante pour la segmentation basée sur un modèle. Le problème de la segmentation est ici traité par estimation statistique d’un maximum a posteriori (MAP). L’optimisation des paramètres de la modélisation- c’est à dire de la position des points de contrôle - est réalisée par le calcul d’une fonction d’énergie globale de champs de Markov (MRF). On combine ainsi les calculs statistiques régionaux et le suivi des frontières avec la connaissance a priori de la forme.Les descripteurs invariants sont estimés par des potentiels de Markov d’ordre 2, tandis que les caractéristiques régionales sont transposées dans un espace de caractéristiques et calculées grâce au théorème de la Divergence.De plus, nous proposons une nouvelle approche pour la segmentation conjointe de l’image et de sa modélisation ; cette méthode permet d’obtenir une segmentation plus fine lorsque la délimitation précise d’un objet est recherchée. Un modèle graphique combinant l’information a priori et les informations de pixel est développé pour réaliser l’unité des modules "top-down" et "bottom-up". La cohérence entre l’image et sa modélisation est assurée par une décomposition qui associe les parties du modèle avec la labellisation de chaque pixel.Les deux champs de Markov d’ordre supérieur considérés sont optimisés par les algorithmes de l’état de l’art. Les résultats prometteurs dans les domaines de la vision par ordinateur et de l’imagerie médicale montrent le potentiel de cette méthode appliquée à la segmentation
In this thesis, we propose a novel framework for knowledge-based segmentation using high-order Markov Random Fields (MRFs). We represent the shape model as a point distribution graphical model which encodes pose invariant shape priors through L1 sparse higher order cliques. Each triplet clique encodes the local shape variation statistics on the angle measurements which inherit invariance to global transformations (i.e. translation,rotation and scale). A sparse higher-order graph structure is learned through MRF training using dual decomposition, producing boosting efficiency while preserving its ability to represent the shape variation.We incorporate the prior knowledge in a novel framework for model-based segmentation.We address the segmentation problem as a maximum a posteriori (MAP) estimation in a probabilistic framework. A global MRF energy function is defined to jointly combine regional statistics, boundary support as well as shape prior knowledge for estimating the optimal model parameters (i.e. the positions of the control points). The pose-invariant priors are encoded in second-order MRF potentials, while regional statistics acting on a derived image feature space can be exactly factorized using Divergence theorem. Furthermore, we propose a novel framework for joint model-pixel segmentation towardsa more refined segmentation when exact boundary delineation is of interest. Aunified model-based and pixel-driven integrated graphical model is developed to combine both top-down and bottom-up modules simultaneously. The consistency between the model and the image space is introduced by a model decomposition which associates the model parts with pixels labeling. Both of the considered higher-order MRFs are optimized efficiently using state-of the-art MRF optimization algorithms. Promising results on computer vision and medical image applications demonstrate the potential of the proposed segmentation methods
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Geremia, Ezequiel. « Spatial random forests for brain lesions segmentation in MRIs and model-based tumor cell extrapolation ». Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00838795.

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The large size of the datasets produced by medical imaging protocols contributes to the success of supervised discriminative methods for semantic labelling of images. Our study makes use of a general and efficient emerging framework, discriminative random forests, for the detection of brain lesions in multi-modal magnetic resonance images (MRIs). The contribution is three-fold. First, we focus on segmentation of brain lesions which is an essential task to diagnosis, prognosis and therapy planning. A context-aware random forest is designed for the automatic multi-class segmentation of MS lesions, low grade and high grade gliomas in MR images. It uses multi-channel MRIs, prior knowledge on tissue classes, symmetrical and long-range spatial context to discriminate lesions from background. Then, we investigate the promising perspective of estimating the brain tumor cell density from MRIs. A generative-discriminative framework is presented to learn the latent and clinically unavailable tumor cell density from model-based estimations associated with synthetic MRIs. The generative model is a validated and publicly available biophysiological tumor growth simulator. The discriminative model builds on multi-variate regression random forests to estimate the voxel-wise distribution of tumor cell density from input MRIs. Finally, we present the "Spatially Adaptive Random Forests" which merge the benefits of multi-scale and random forest methods and apply it to previously cited classification and regression settings. Quantitative evaluation of the proposed methods are carried out on publicly available labeled datasets and demonstrate state of the art performance.
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Livres sur le sujet "MRAS TECHNIQUE"

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Springs, Alice. Mrs. Newton. Köln : Taschen, 2004.

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Symposium D on Analytical Techniques for the Characterization of Compound Semiconductors (1990 Strasbourg, France). Analytical techniques for the characterization of compound semiconductors : Proceedings of Symposium D on Analytical Techniques for the Characterization of Compound Semiconductors of the 1990 E-MRS Fall Conference, Strasbourg, France, November 27-30, 1990. Amsterdam : North-Holland, 1991.

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Symposium F on Techniques and Challenges for 300 mm Silicon (1998 Strasbourg, France). Techniques and challenges for 300 mm silicon : Processing, characterization, modelling and equipment : proceedings of Symposium F on Techniques and Challenges for 300 mm Silicon of the E-MRS 1998 Spring Conference, Strasbourg, France, 16-19 June 1998. Amsterdam : Elsevier, 1999.

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Pass the MRCS : All the Techniques You Need (MRCS Study Guides). Saunders Ltd., 2001.

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Gattringer, Thomas, Christian Enzinger, Stefan Ropele et Franz Fazekas. Vascular imaging (CTA/MRA). Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198722366.003.0008.

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Non-invasive computed tomography angiography (CTA) and magnetic resonance angiography (MRA) constitute an integral part of the diagnostic workup of stroke patients, which—among the various techniques to image the complex cerebrovascular tree—can be conceptually placed between duplex sonography and digital subtraction angiography. CTA and especially MRA can be performed with different techniques and protocols that need to be used according to the clinical questions. In the setting of acute ischaemic stroke with the therapeutic option of endovascular thrombectomy, the rapid and reliable detection of large vessel occlusion has become of paramount importance. Both CTA and MRA can accomplish this and there is no need for contrast material when performing intracranial MRA. Vascular imaging is also essential to identify vessel-related causes of stroke such as large artery atherosclerosis, dissection, and some forms of arteritis mandating specific management or therapeutic intervention to avoid recurrence. Considering these aspects, frequent and targeted use of CTA or MRA is highly encouraged and especially relevant in young patients with stroke.
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Missing Being Mrs. Monarch, 2004.

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Thrumurthy, Sri G., Tania S. De Silva, Zia M. Moinuddin et Stuart Enoch. EMQs for the MRCS Part A. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199645640.001.0001.

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Specifically designed to help candidates revise for the MRCS exam, this book features 250 extended matching questions divided into 96 themes, covering the whole syllabus. Containing everything candidates need to pass the MRCS Part A EMQ section of the exam, the book focuses intensively on topics relating to principles of surgery-in-general, including peri-operative care, post-operative management and critical care, surgical technique and technology, management and legal issues in surgery, clinical microbiology, emergency medicine and trauma management, and principles of surgical oncology. The high level of detail included within the questions and their explanations allows effective self-assessment of knowledge and quick identification of key areas requiring further attention. Varying approaches to extended matching questions are used, giving effective exam practice and guidance through revision and exam technique. This includes clinical case questions, positively-worded questions, requiring selection of the most appropriate of relatively correct answers; 'two-step' or 'double-jump' questions, requiring several cognitive steps to arrive at the correct answer; as well as factual recall questions, prompting basic recall of facts.
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Gomes, William A. Neuroimaging of Epilepsy. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199937837.003.0045.

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Neuroimaging is essential for clinical care and basic research in epilepsy. MRI is the primary tool, but adjunctive techniques are commonly employed including MRS, PET, SPECT, and MEG. These techniques facilitate localization and characterization of seizure foci prior to epilepsy surgery, and also allow preoperative assessment of risk to eloquent brain regions. Evaluation of patients with MRI-negative epilepsy remains a major clinical challenge and motivation for contemporary research.
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Flournoy, Deborah Brazzell. Mrs. Flournoy's Collection of Quotes and Affirmations : Learning Life's Lessons. Your Online Publicist, 2021.

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Flournoy, Deborah Brazzell. Mrs. Flournoy's Collection of Quotes and Affirmations : Learning Life's Lessons. Your Online Publicist, 2021.

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Chapitres de livres sur le sujet "MRAS TECHNIQUE"

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Pattison, Julian. « Techniques ». Dans Mrs Dalloway by Virginia Woolf, 59–68. London : Macmillan Education UK, 1987. http://dx.doi.org/10.1007/978-1-349-09357-1_4.

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Runge, Val M., et Johannes T. Heverhagen. « Advanced Non-Contrast MRA Techniques ». Dans The Physics of Clinical MR Taught Through Images, 178–79. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-85413-3_81.

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O’Doherty, Toni, Róisín Nic Amhlaoibh et Martin Clynes. « Analysis of Specific and Differentially Expressed mRNAs in Cell Culture ». Dans Animal Cell Culture Techniques, 582–99. Berlin, Heidelberg : Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-80412-0_32.

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Kumari, Seema, et Rekha Yadav. « Spin-Transfer Torque MRAM with Emerging Sensing Techniques ». Dans Lecture Notes in Electrical Engineering, 15–25. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-7993-4_2.

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Francone, Marco, Michele Anzidei, Ilaria Iacucci, Francesco Vullo et Carlo Catalano. « Image Acquisition Technique and Sequences Contrast-Enhanced MRA ». Dans MR Angiography of the Body, 17–25. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-79717-3_3.

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Abuzneid, Abdelshakour, et Brandon J. Stark. « Improving BGP Convergence Time via MRAI Timer ». Dans Novel Algorithms and Techniques in Telecommunications and Networking, 105–10. Dordrecht : Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3662-9_17.

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Uhlmann, Volker, Eilhard Mix et Arndt Rolfs. « Application of In Situ-PCR for the Detection of Intracellular mRNAs ». Dans Modern Applications of DNA Amplification Techniques, 65–76. Boston, MA : Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-5379-3_7.

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Kulthe, Shubham, Chandra Shekher Purohit, Saibal Manna, R. Sudha, B. Jaganatha Pandian et Anis Kazi. « Performance Analysis of Interactive Thermal Process Using Various MRAC Techniques ». Dans Lecture Notes in Electrical Engineering, 97–109. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-6772-4_10.

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Oliveira, Duarte C., Hermínia de Lencastre et Alexander Tomasz. « Evolution of Molecular Techniques for the Characterization of MRSA Clones ». Dans Antibiotic Discovery and Development, 571–92. Boston, MA : Springer US, 2011. http://dx.doi.org/10.1007/978-1-4614-1400-1_17.

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de Graaf, Robin. « Techniques-MRS, fMRI, 13C NMR, Indirect Detection of 13C ». Dans Brain Energetics and Neuronal Activity, 31–52. Chichester, UK : John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470020520.ch3.

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Actes de conférences sur le sujet "MRAS TECHNIQUE"

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Meryem, Benakcha, Benakcha Abdelhamid, Ammar Abdelkarim et Zouzou Salah Eddine. « Real-time control of PMSM motor drive based MRAS-STC technique ». Dans 2022 19th International Multi-Conference on Systems, Signals & Devices (SSD). IEEE, 2022. http://dx.doi.org/10.1109/ssd54932.2022.9955913.

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Kumar, Pradeep, Sandeep Dhundhara et Ruchi Makin. « Performance analysis of PMSM drive based on FOC technique with and without MRAS method ». Dans 2016 International Conference on Recent Advances and Innovations in Engineering (ICRAIE). IEEE, 2016. http://dx.doi.org/10.1109/icraie.2016.7939492.

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Qian, Kai, Tao Wang, Xiaojun Zou, Wei Song, Liukai Yuan et Liangmo Wang. « MRAS-Based Sensorless Vector Control of Wheel Motors ». Dans WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0538.

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<div class="section abstract"><div class="htmlview paragraph">Traditional vector control needs the installation of mechanical sensors to gather rotor position and speed information in order to enhance the control performance and dynamic quality of electric vehicle wheel motors, which increases system cost and reduces system reliability and stability. On the basis of Popov's super-stability theory, an appropriate adjustable model and reference model are constructed, and the system's reference adaptive law is determined. Furthermore, to solve the problem of the standard PI regulator's poor anti-interference capabilities in speed controllers, the approach of utilizing a sliding-mode speed controller in the speed loop is presented. Finally, a MATLAB/SIMULINK simulation model is created to simulate the motor in three scenarios: no-load start, abrupt speed change, and sudden load change, and a permanent magnet synchronous motor experimental platform is created to validate the control approach. The findings demonstrate that this technique can estimate speed and position data accurately and fast, with strong immunity to interference and robustness, and that it can fulfill the demands of actual wheel motor control performance.</div></div>
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Cirrincione, M., M. Pucci, G. Cirrincione et G. A. Capolino. « An Enhanced Neural MRAS Sensorless Technique based on Minor-Component-Analysis for Induction Motor Drives ». Dans Proceedings of the IEEE International Symposium on Industrial Electronics. IEEE, 2005. http://dx.doi.org/10.1109/isie.2005.1529181.

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Mehreganfar, Mohammad, Mohammad Hosein Saeedinia, S. Alireza Davari et Davood Arab Khaburi. « Direct power control of AFE rectifier by line voltage sensorless predictive technique and MRAS inductance estimator ». Dans 2018 9th Annual Power Electronics, Drives Systems and Technologies Conference (PEDSTC). IEEE, 2018. http://dx.doi.org/10.1109/pedstc.2018.8343804.

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Weisheng Yan, Hai Lin, Hong Li, Huiping Li et Jian Lu. « A MRAS based speed identification scheme for a PM synchronous motor drive using the sliding mode technique ». Dans 2009 International Conference on Mechatronics and Automation (ICMA). IEEE, 2009. http://dx.doi.org/10.1109/icma.2009.5246414.

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Rkiai, Chaima, Houssem Chaouali, Hichem Othmani et Abdelkader Mami. « Sensorless speed control of a 3 phased asynchronous machine based on MRAS observer and fuzzy logic control technique ». Dans 2017 International Conference on Engineering & MIS (ICEMIS). IEEE, 2017. http://dx.doi.org/10.1109/icemis.2017.8273040.

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Tarkhani, Rakia, Saber Krim et Mohamed Faouzi Mimouni. « Design of a Sensorless Rotor Flux Oriented Vector Control Technique Based on MRAS Speed Observer for an Induction Machine ». Dans 2023 IEEE International Conference on Advanced Systems and Emergent Technologies (IC_ASET). IEEE, 2023. http://dx.doi.org/10.1109/ic_aset58101.2023.10151242.

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Rao, Purushottama, Jayaram Nakka et R. Shekar. « Sensorless vector control of Induction machine using MRAS techniques ». Dans 2013 International Conference on Circuits, Power and Computing Technologies (ICCPCT). IEEE, 2013. http://dx.doi.org/10.1109/iccpct.2013.6529053.

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Yassine, Beddiaf, Zidani Fatiha et Larbi Chrifi-Alaoui. « New MRAS Approach for Sensorless control of IM ». Dans 2019 19th International Conference on Sciences and Techniques of Automatic Control and Computer Engineering (STA). IEEE, 2019. http://dx.doi.org/10.1109/sta.2019.8717287.

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Rapports d'organisations sur le sujet "MRAS TECHNIQUE"

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Sun, Lina, Yanan Han, Hua Wang, Huanyu Liu, Shan Liu, Hongbin Yang, Xiaoxia Ren et Ying Fang. MicroRNAs as Potential Biomarkers for the Diagnosis of Inflammatory Bowel Disease : A Systematic Review and Meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, février 2022. http://dx.doi.org/10.37766/inplasy2022.2.0027.

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Review question / Objective: The purpose of this systematic review was to systematically review the clinical studies regarding miRNAs as diagnostic biomarkers for inflammatory bowel disease and assess the overall diagnostic accuracy of miRNAs. Condition being studied: The symptoms of inflammatory bowel disease (IBD) are highly variable. The diagnosis of IBD must be made through medical history, physical, laboratory, radiologic, endoscopic, and histological examinations. However, these diagnostic techniques are not specific and sometimes even equivocal. Therefore, reliable biomarkers are urgently needed in the diagnosis of IBD. Several clinical and preclinical researches have shown that dysregulated microRNAs (miRNAs) play a crucial role in IBD development. miRNAs, as single-stranded noncoding RNAs that contain 22-24 nucleotides, can post-transcriptionally regulate gene expression by blocking mRNA translation or degrading target mRNAs. miRNAs are widely involved in physiological and pathological cellular processes, such as differentiation, proliferation and apoptosis. Besides, they are stable, noninvasive, and resistant to degradation by ribonucleases, making them valuable targets in the diagnosis, monitoring, prognosis, and treatment of diseases. To date, inconsistent results have been found about miRNA expression profiling in the patients with IBD. Moreover, the diagnostic accuracy of miRNAs for IBD has not been reported in any meta-analysis.
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Stern, David B., et Gadi Schuster. Manipulation of Gene Expression in the Chloroplast : Control of mRNA Stability and Transcription Termination. United States Department of Agriculture, décembre 1993. http://dx.doi.org/10.32747/1993.7568750.bard.

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Chloroplasts are the site of photosynthesis and of other essential biosynthetic activities in plant cells. Chloroplasts are semi-autonomous organelles, since they contain their own genomes and protein biosynthetic machinery, but depend on the coordinate expression of nuclear genes to assemble macromolecular complexes. The bioeingineering of plants requires manipulation of chloroplast gene expression, and thus a knowledge of the molecular mechanisms that modulate mRNA and protein production. In this proposal the heterotrophic green alga Chlamydomonas reinhardtii has been used as a model system to understand the control and interrelationships between transcription termination, mRNA 3' end processing and mRNA stability in chloroplasts. Chlamydomonas is a unique and ideal system in which to address these issues, because the chloroplast can be easily manipulated by genetic transformation techniques. This research uncovered new and important information on chloroplast mRNA 3' end formation and mRNA stability. In particular, the 3' untranslated regions of chloroplast mRNAs were shown not to be efficient transcription terminators. The endonucleolytic site in the 3' untranslated region was characterized by site directed mutagensis and the role of several 3' untranslated regions in modulating RNA stability and translation has been studied. This information will allow us to experimentally manipulate the expression of chloroplast genes in vivo by post-transcriptional mechanisms, and should be widely applicable to other higher plant systems.
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Meidan, Rina, et Robert Milvae. Regulation of Bovine Corpus Luteum Function. United States Department of Agriculture, mars 1995. http://dx.doi.org/10.32747/1995.7604935.bard.

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The main goal of this research plan was to elucidate regulatory mechanisms controlling the development, function of the bovine corpus luteum (CL). The CL contains two different sterodigenic cell types and therefore it was necessary to obtain pure cell population. A system was developed in which granulosa and theca interna cells, isolated from a preovulatory follicle, acquired characteristics typical of large (LL) and small (SL) luteal cells, respectively, as judged by several biochemical and morphological criteria. Experiments were conducted to determine the effects of granulosa cells removal on subsequent CL function, the results obtained support the concept that granulosa cells make a substaintial contribution to the output of progesterone by the cyclic CL but may have a limited role in determining the functional lifespan of the CL. This experimental model was also used to better understand the contribution of follicular granulosa cells to subsequent luteal SCC mRNA expression. The mitochondrial cytochrome side-chain cleavage enzyme (SCC), which converts cholesterol to pregnenolone, is the first and rate-limiting enzyme of the steroidogenic pathway. Experiments were conducted to characterize the gene expression of P450scc in bovine CL. Levels of P450scc mRNA were higher during mid-luteal phase than in either the early or late luteal phases. PGF 2a injection decreased luteal P450scc mRNA in a time-dependent manner; levels were significantly reduced by 2h after treatment. CLs obtained from heifers on day 8 of the estrous cycle which had granulosa cells removed had a 45% reduction in the levels of mRNA for SCC enzymes as well as a 78% reduction in the numbers of LL cells. To characterize SCC expression in each steroidogenic cell type we utilized pure cell populations. Upon luteinization, LL expressed 2-3 fold higher amounts of both SCC enzymes mRNAs than SL. Moreover, eight days after stimulant removal, LL retained their P4 production capacity, expressed P450scc mRNA and contained this protein. In our attempts to establish the in vitro luteinization model, we had to select the prevulatory and pre-gonadotropin surge follicles. The ratio of estradiol:P4 which is often used was unreliable since P4 levels are high in atretic follicles and also in preovulatory post-gonadotropin follicles. We have therefore examined whether oxytocin (OT) levels in follicular fluids could enhance our ability to correctly and easily define follicular status. Based on E2 and OT concentrations in follicular fluids we could more accurately identify follicles that are preovulatory and post gonadotropin surge. Next we studied OT biosynthesis in granulosa cells, cells which were incubated with forskolin contained stores of the precursor indicating that forskolin (which mimics gonadotropin action) is an effective stimulator of OT biosynthesis and release. While studying in vitro luteinization, we noticed that IGF-I induced effects were not identical to those induced by insulin despite the fact that megadoses of insulin were used. This was the first indication that the cells may secrete IGF binding protein(s) which regonize IGFs and not insulin. In a detailed study involving several techniques, we characterized the species of IGF binding proteins secreted by luteal cells. The effects of exogenous polyunsaturated fatty acids and arachidonic acid on the production of P4 and prostanoids by dispersed bovine luteal cells was examined. The addition of eicosapentaenoic acid and arachidonic acid resulted in a dose-dependent reduction in basal and LH-stimulated biosynthesis of P4 and PGI2 and an increase in production of PGF 2a and 5-HETE production. Indomethacin, an inhibitor of arachidonic acid metabolism via the production of 5-HETE was unaffected. Results of these experiments suggest that the inhibitory effect of arachidonic acid on the biosynthesis of luteal P4 is due to either a direct action of arachidonic acid, or its conversion to 5-HETE via the lipoxgenase pathway of metabolism. The detailed and important information gained by the two labs elucidated the mode of action of factors crucially important to the function of the bovine CL. The data indicate that follicular granulosa cells make a major contribution to numbers of large luteal cells, OT and basal P4 production, as well as the content of cytochrome P450 scc. Granulosa-derived large luteal cells have distinct features: when luteinized, the cell no longer possesses LH receptors, its cAMP response is diminished yet P4 synthesis is sustained. This may imply that maintenance of P4 (even in the absence of a Luteotropic signal) during critical periods such as pregnancy recognition, is dependent on the proper luteinization and function of the large luteal cell.
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